Equilibrated copyboard

ABSTRACT

A pivoted holder for flat material such as a copyboard or similar device for use in a light exposure system is mounted on a support for tiltable movement selectively between an expose or process position and a loading position and includes elastic means interconnecting the copyboard and the support in a manner to urge the holder toward an equilibrium position approximately mid-way between the two extreme positions, thereby implementing actuation of the copyboard by an operator between selected positions.

[451 July 25,1972

ABSTRACT FOREIGN PATENTS OR APPLICATIONS 8/1960GreatBritain........................

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United States Patent Nothmann [54] EQUILIBRATED COPYBOARD [72] Inventor:Gerhard A. Nothmann, Wilmette, lll.

Robertson Photo-Mechanix, Plaines,lll.

Inc., Des

[73] AsSgnee: Primary Examiner-Samuel S. Matthews AssistantExaminer-Russell B. Adams, Jr. [22] Filed: Aug. 31, 1970 Attorney-Hill,Sherman, Meroni, Gross & Simpson [21] Appl. No.: 68,118

A pivoted holder for flat material such as a copyboard or similar devicefor use in a light exposure system is mounted on 40/341 a support fortiltable movement selectively between an expose 40 I3 1 267 50 orprocess position and a loading position and includes elastic [51] Int.[58] Field ol'Search....

means interconnecting the copyboard and the support in a manner to urgethe holder toward an equilibrium position ap- Relerences Citedproximately mid-way between the two extreme positions, therebyimplementing actuation of the copyboard by an .267/150 XShepard...............................355/75 X h g m .m o w a -m m 0 D.3 d m m c m e l l m w a M u m r .5 "v e I w a h e b m m r e D- O SHEET 1[IF 2 PATENTEDJUL 25 I972 EQUILIBRATED COPYBOARD BACKGROUND OF THEINVENTION 1. Field of the Invention This invention generally relates tothe graphic arts and more specifically to a copyboard, vacuum frame orsimilar device in which flat material is retained for processing orexposure in a process camera or other light exposure system, and moreparticularly refers to a pivoted copyboard having means for urging thesame toward an equilibrium position disposed approximately mid-waybetween an operating position and a loadingunloading position.

2. Description of the Prior Art Light exposure systems, for use ingraphic arts, printing, photofabrication and similar applications,generally include a copyboard or similar device for holding original,flat material to be copied, processed and/or exposed. For convenience inloading and unloading, and in order to provide an optimum physicalarrangement of the machine, the copyboards are usually journalled in themachine frame for pivotal or tiltable movement between aloading-unloading position and a working or exposing position. When thecopyboard is in the loading-unloading position, an operator inserts orotherwise constrains the material to be copied or exposed in or on thecopyboard and then moves the copyboard to the working position, whereinthe material is arranged for optimum photographic exposure or otherworking conditions. Most commonly, the loading-unloading position isapproximately a horizontal position, whereas the working or exposingposition may be a vertical position or possibly a horizontal positionwherein the copyboard is rotated approximately one-half revolution fromthe loading-unloading position, as is the case in a plate exposureapparatus.

Since the copyboard normally contains glass or similar fragile material,and since its location in the working or exposing position must beprecise to obtain optimum results, considerable care must be exercisedby the operator in pivoting or otherwise moving the copyboard from theloading-unloading position to the working position. In large processcameras and other graphic arts devices, the copyboards may be relativelylarge and heavy, thereby requiring considerable effort on the part ofthe operator to move the copyboard in a controlled manner and, inparticular, to guide the copyboard to its working position withoutdamage thereto or to the material contained therein.

Heretofore, provisions have been made for reducing the manual effort andskill required in the operation of copyboards. Completely automaticcopyboards, normally operated by electrical motors or electrohydrauliccontrol systems, have been used. Semi-automatic means utilizingdash-pots or similar shock absorbers, have been used to facilitate thecopyboard movement and, in particular, to insure that the copyboardarrives at its working position with a sufficiently low terminal speedto avoid damage or excessive overtravel.

SUMMARY OF THE INVENTION In accordance with the present invention, acopyboard mounted on a support for tiltable movement selectively betweena loading position and an expose or process position includes elasticmeans interconnecting the copyboard and the support so that it is urgedtoward an equilibrium position selected to be approximately mid-waybetween the extreme operating or working positions.

Since the copyboard is constrained to rotate about a fixed pivot axis,the elastic means, which may be an elastic member, such as a mechanicalspring, causes the copyboard to oscillate about the equilibrium positionin a manner similar to an elastic pendulum. The frequency of thoseoscillations, and therefore the speed of movement, is dependent upon therotational inertia of the copyboard and upon the parameters of theelastic member or other elastic means. The amplitude or excursion of theoscillations depends on the initial position of the copyboard relativeto its equilibrium position. At each of the two copyboard,

extreme positions, the rotational speed of the copyboard is zero andreaches a maximum value at the mid-point of the oscillation, alternatelyin either direction. If allowed to oscillate freely, the excursion ofthe oscillation will remain nearly constant and decrease from cycle tocycle, only by an amount determined by friction and air resistance.Since the copyboard comes to rest at each of the extreme positions, itis possible to hold the copyboard at rest for a finite period of time,at either of those positions, and then release the copyboard forcontinuation of the oscillatory motion or to permit movement to thealternate position.

Spring loaded detents, which may be actuated by the operator at anappropriate time, constrain the copyboard selectively at the loadingposition or at the expose or process position. Each detent holds thecopyboard in the corresponding position and, upon release by theoperator, releases the copyboard for movement to the alternate position.

If desired, the location of the loading position and the expose orprocess position, and thus of the appropriate detents, relative to theequilibrium position, may be selected so that the copyboard will movefrom the loading position, after appropriate release of the detent, tothe expose position without requiring manual assistance by the operator.Thus, the copyboard will arrive at the expose position at a very lowspeed only sufficient to insure action of the detent, thereby to allowthe detent to hold the copyboard in the expose position. Conversely,when the copyboard is released from the expose position, by operation ofthe appropriate detent, the copyboard moves from that position to andpast the equilibrium position and continues toward the loading position.However, a small additional effort, by the operator, is required tocomplete the travel of the copyboard to the loading position and toinsure actuation of the detent for holding.

With the copyboard of the present invention, the effort required by theoperator is limited to the force necessary for actuating the detents aswell as the small effort necessary to bring the copyboard, during thefinal portion of its motion, into the loading position. Those forces, aswell as the care and attentionrequired, are significantly smaller thanthose which would normally be required to move the copyboard through itstotal excursion in the absence of the elastic pendulum means of thepresent invention. Furthermore, additional convenience is provided,since the efforts which the operator needs to exert for this operationoccur at a time when he is normally in the vicinity of the copyboard.Typically, after loading copy material into the copyboard, and thenactuating the appropriate detent, the operator prefers to attend toother duties or operations on the equipment and not to return to thecopyboard until the machine cycle has advanced to a point where materialin the copyboard is to be removed and replaced by material for the nextcycle. At that time, the operator would again approach the copyboard,actuate the appropriate detent, and remain at the copyboard to assist inthe motion which beings the copyboard into the loading position, atwhich time he would proceed with unloading of the material previouslyexposed or processed and the loading of the material required for thenext cycle or operation.

It should be understood that the friction and air resistance encounteredby the copyboard in its movement between extreme positions should beminimized, by the use of low friction pivot bearing materials andavoidance of attachments to the to provide greatest effectiveness of themechanism. However, even when this has been accomplished, the mechanismstill requires some manual assistance during the final portion of one ofthe alternate movements, specifically the movement into the loadingposition; this assistance compensates for the unavoidable friction airresistance and detent forces described.

Accordingly, it is an object of the present invention to provide acopyboard having means which minimize the manual effort, skill, andattention involved in operating the copyboard, reduces the speed withwhich the copyboard arrives at each of its extreme, tenninal positionsand therefore the potential damage or disturbance, and provides amechanism of minimum complexity and cost.

Further, it is an object of the present invention to provide a pivotedcopyboard having an elastic member or other elastic means operativelyattached thereto in a manner to form an elastic pendulum having anequilibrium position located between the extreme positions of thecopyboard, thereby implementing movement from either one of the extremepositions to the alternate position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of acopyboard embodying the features of the present invention;

FIG. 2 is an elevational view, with portions broken away to showadditional details, of a side support for the copyboard of FIG. 1 andillustrates the mechanism of the present invention housed within thesupport;

FIG. 3 is a sectional view taken substantially along the line III-III ofFIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thedrawings, a copyboard mechanism, constructed in accordance with thepresent invention and generally indicated at 10, is joumalled between apair of upright supports 11, 11, which in turn are supported for slidingmovement on rails 12 forming a bed for a graphic arts camera. Such aprocess camera also includes a rear case, for supporting film or similarmaterial, which may be supported on the rails 12 of the camera bed at anend thereof opposite the copyboard 10. It generally includes a frontlens case carried on the rails 12 for sliding movement toward and awayfrom the copyboard in a manner to focus the camera. The cameraconstruction also includes illumination means such as the lights 14 forsuitably illuminating the copyboard 10.

Although the present invention is described in reference to a copyboardfor a graphic arts camera, it should be understood that the principlesof the present invention are equally applicable to other copy-boards orsimilar devices generally utilized in the graphic arts field. One suchother device may include a plate exposure apparatus having a pivotedcopyboard or vacuum frame adapted for holding flat material in aposition suitable to provide a latent image on an offset or similarprinting plate.

The copyboardincludes a cover or front section 16 hingedly connected toa base or back section 17 for pivotal movement relative thereto. Thebase or back section 17 provides a support surface which may include aresiliently mounted pad against which a piece of copy is disposed, andthe cover 16 has a transparent window covering and restraining the pieceof copy, thereby to clamp the piece of copy between the copyboardsections.

Each of the upright supports 11 includes a casting, or similarstructure, having a generally U-shaped configuration in transversecross-section and characterized by an outer wall 21 and a pair ofparallel side walls 22, 22. An upper wall 23 and a base 24 respectivelyclose upper and lower ends of the side supports 11, thereby forming acavity 26 in each of the supports.

A pair of pivot pins 27, 27 are joumalled in the copyboard at oppositesides thereof and in appropriate bearing means. An embossment 28 formedin an upper corner of each of the supports 11 has an aperture 29 formedtherein for receiving the pivot pins 27, thereby to mount the copyboard10 for tiltable or pivotable movement about a generally horizontallyextending pivot axis. The copyboard 10 may be tilted selectively betweena vertical, working or expose position, as illustrated in FIG. 1, and ahorizontal loading-unloading or process position. It may be seen that,for other applications or configurations, the expose position and theloading position may be selected to be at positions other than thevertical and the horizontal, for example the loading position may behorizontal and the working or expose position may be substantiallyhorizontal but rotated approximately one-half revolution from theloading-unloading or process position.

In order to constrain the copyboard 10 in the selected one of thealternate positions, a pair of detent means 31 and 32 are provided inone of the side supports 1 1 for cooperation with a pair ofappropriately disposed detent blocks as at 33. Each of the detent means31 and 32 has a handle 34 enabling manual movement of the detent againsta spring force in a manner to release the detent, thereby permittingmovement of the copyboard 10 to the alternate position. Each of thedetent blocks 33 has a base 36 attached to the back section 17 of thecopyboard 10 by suitable fasteners, such as screws as at 37. Anoutwardly ofiset abutment 38 on the detent block base 36 is engaged bythe associated one of the detent means 31 or 32 in a manner to lock orconstrain the copyboard in the selected position until the operatorreleases the detent to move the copyboard to the alternate position.

In accordance with the present invention, elastic means are attached tothe copyboard 10 at a location radially offset from the pivot axis in amanner to cooperate with the copyboard for forming an elastic pendulumhaving an equilibrium position between the loading-unloading positionand the exposing or working position, thereby to assist an operator inmoving the copyboard from one of the positions to the alternate positionwith a minimum amount of effort being required.

As illustrated in the drawings, the elastic means include a spring 41having one end portion as at 42 attached to one of the side supports 11.An L-shaped bracket 43 has one leg portion 44 secured to the supportbase 24 by suitable fasteners, such as screws as at 46. An aperture 47formed in the other leg portion 48 receives a loop 49 formed on the endportion 42 of the spring 41, thereby anchoring the spring to the sidesupport 1 l.

An inextensible, flexible member such as a segment of a roller chain 51interconnects the other free end 52 of the spring 41 to an outer end 53of an attachment arm 54. The attachment arm 54 extends at right anglesto the copyboard 10 and has a bearing means 56 formed in one end thereoffor receiving the pivot pin 27. A pair of attachment bolts 57, 57 flankthe bearing means 56 and secure the attachment arm 54 to the copyboardbase section 17. When the copyboard 10 is disposed in the vertical,working position, the attachment arm 54 projects rearwardly, asillustrated 'by solid lines in FIG. 3. As the copyboard 10 pivots fromthe working position to the loading-unloading position, the attachmentarm 54 swings through an arcuate path and assumes a downwardlyprojecting position, as shown by dotted lines in FIG. 3, when thecopyboard arrives at the loading-unloading position.

In order to apply the tension force to the copyboard in a manner to forman elastic pendulum having an equilibrium position between the alternateextreme positions, i.e. the loading-unloading position and the workingposition, and to confine the mechanism within the cavity 26 of one orboth of the side supports 11, the inextensible, flexible member 51 ispartially wrapped around rotary support means, such as a chain sprocketgenerally indicated at 59, thereby providing a method for changing thedirection of force and motion of the elastic means. If the pivot axispasses through the center of gravity of the copyboard 10, theequilibrium position would be a position wherein the upper part of theinextensible, flexible member 51 is disposed along a line segmentpassing through the copyboard pivot axis and tangent to the rotarysupport means 59. Since the alternate, extreme positions are angularlyspaced apart by an angle of in the case described above, the equilibriumposition of the inextensible, flexible member 51 lies along a linedisposed at 45 from the horizontal and vertical positions of theattachment arm 54. If desired, the pivot axis of the copyboard 10 may beselected relative to the copyboard center of gravity to slightly biasthe copyboard toward the vertical, working position. In that case, thespring 41 exerts a force counterbalancing the biasing force whenever thecopyboard 10 is at the equilibrium position. The equilibrium position isthen displaced slightly from the 45 degree position described.

As illustrated in the drawings, the inextensible, flexible member is aroller chain having one end portion 61 attached to the free end 52 ofthe spring 41 and having the other end portion 62 attached to the outerend 53 of the attachment arm 54. A loop 63 at the free end 52 of thespring 41 engages one of the rollers as at 64 of the chain 51 forattaching the same to the spring. A pin 66 having an inner end portionpress fit into an appropriate aperture 67 formed in an outer end 53 ofthe attachment arm 54 has a bearing 68 rotatably carried on the outerend portion in alignment with the chain 51. A strap 69 wrapped aroundthe bearing 68 is secured to the upper end 62 of the chain 51 byappropriate attachment means as at 71, thereby to enable pivotalmovement of the chain relative to the arms as the arm travels throughits arcuate path with the tiltable or pivotal movement of the copyboard10.

The rotary support means 59 include a sprocket 72 engaged by the chain51. An L-shaped bracket 73 supports the sprocket 72 and has one leg 74attached to the support side wall 22 by a pair of nut and boltassemblies 76, 76. In order to enable adjustment or selectivepositioning of the sprocket 72 relative to the copyboard pivot axis, theother leg portion 77 of the bracket 73 has a vertically extending,elongated slot 78 formed therein. A bolt 79 passes through a cylindricalspacer in the bore 81 of the sprocket 72 and through the slot 78 and hasan outer threaded portion receiving a nut 82, thereby to retain thesprocket in a selected position along the slot of the bracket 73.

Thus, when an operator releases the detent 32 to enable the copyboardfor movement from the loading-unloading position, the combined forcesprovided by offsetting the copyboard pivot axis from the center ofgravity and by the tension spring 41 pivot the copyboard 10 toward theworking position. Since the equilibrium position is offset from aprecise midpoint between the two alternate extreme positions and towardthe working position, the copyboard l0 arrives at the working positionwith sufficient force and velocity to actuate the detent 31, whichsubsequently constrains the copyboard in that position. After thecopyboard 10 moves through the equilibrium position, the tension spring41 applies a decelerating force to the copyboard 10 to insure that thecopyboard reaches the working position with a sufficiently low terminalspeed to avoid damage to the glass and to avoid accidental displacementof the piece of copy constrained in the copyboard. By adjusting theposition of the sprocket 72 along the slot 78, the equilibrium positionof the copyboard 10 may be selected in a manner to provide the desiredresults, eg biasing the copyboard toward either one of the alternatepositions and, more specifically, as heretofore described, toward theworking positron.

The degree to which the equilibrium position should be offset from thegeometric mid-point or mid-position is a function of the friction in thecopyboard journals, air resistance, and the force necessary to cock thedetents. In most practical situations these should be small factors sothat the equilibrium position will be very close to the mid-point,thereby affording the advantages of the present invention.

Although various modifications might be suggested by those versed in theart,-it should be understood that I wish to embody within the scope ofthe patent warranted hereon all such modifications as reasonably andproperly come within the scope of my contribution to the art.

I claim as my invention:

1. in a light exposure system, a copyboard mechanism having means forconstraining a piece of copy; support means mounting said copyboard formovement about a pivot axis selectively between two alternate positionsincluding a first position for loading and unloading and a secondworking position angularly disposed from the first position; means forreleasably constraining said copyboard in a selected one of thealternate positions; means for assisting movement of said copyboardbetween said alternate positions, said means inclu ng means for applyrngan elastrc force to sard copyboard at a location radially offset fromthe copyboard pivot axis; said means for assisting movement of saidcopyboard between the alternate positions including an inextensible,flexible member; attachment means securing one end portion of saidflexible member to said copyboard at a location radially offset fromsaid copyboard pivot axis; elastic means for applying tension to saidinextensible, flexible member and being attached to the other endportion thereof; rotary support means having said flexible memberpartially wrapped therearound and said rotary support means beingdisposed relative to said copyboard pivot axis and to the point wheresaid flexible member is attached to the copyboard to thereby cause saidtension means to urge said copyboard toward an equilibrium positiondisposed between the alternate positions; said rotary support meanshaving an axis of rotation, said rotary support means being mounted forselective adjustment of its axis of rotation along a path disposed toadjust the equilibrium position upon adjustment of said rotary supportmeans.

2. In a light exposure system a copyboard mechanism having means forconstraining a piece of copy; support means mounting said copyboard fortiltable movement about a pivot axis selectively between two alternatepositions including a first position for loading and unloading and asecond working position angularly related to said first position; meansfor releasably constraining said copyboard in a selected one of thealternate positions; means for assisting movement of said copyboardbetween the alternate positions through application of an elastic forceto said copyboard at a location radially offset from the copyboard pivotaxis; said means for assisting movement of said copyboard between thealternate positions including an inextensible, flexible member having anattachment means securing one end portion of said flexible member tosaid copyboard at a location radially offset from the copyboard pivotaxis, elastic means for applying tension to said inextensible, flexiblemember and being attached to the other end portion thereof; saidcopyboard being mounted on said support means so that said copyboardpivot axis is offset from the center of gravity of said copyboard in adirection to bias said copyboard toward one of the alternate positionsand relative to said rotary support means; means constraining saidcopyboard in a selected one of the alternate positions and beingreleasable to enable movement of said copyboard to the other one of thealternate positions; and said rotary support means being selectivelydisposed so that said copyboard arrives at the working position with asufficiently low velocity to prevent damage of the copyboard, itscomponents, and its contents.

3. The invention according to claim 1 wherein said inextensible,flexible member includes a length of roller chain; said rotary supportmeans including a sprocket having said chain engaged therewith.

4. The invention according to claim 2 and further characterized bydetent means engageable with portions of said copyboard for constrainingthe copyboard in a selected one of the two alternate extreme positionsand being releasable to permit movement to the alternate one of saidpositions under the urging of said elastic means.

1. In a light exposure system, a copyboard mechanism having means forconstraining a piece of copy; support means mounting said copyboard formovement about a pivot axis selectively between two alternate positionsincluding a first position for loading and unloading and a secondworking position angularly disposed from the first position; means forreleasably constraining said copyboard in a selected one of thealternate positions; means for assisting movement of said copyboardbetween said alternate positions, said means including means forapplying an elastic force to said copyboard at a location radiallyoffset from the copyboard pivot axis; said means for assisting movementof said copyboard between the alternate positions including aninextensible, flexible member; attachment means securing one end portionof said flexible member to said copyboard at a location radially offsetfrom said copyboard pivot axis; elastic means for applying tension tosaid inextensible, flexible member and being attached to the other endportion thereof; rotary support means having said flexible memberpartially wrapped therearound and said rotary support means beingdisposed relative to said copyboard pivot axis and to the point wheresaid flexible member is attached to the copyboard to thereby cause saidtension means to urge said copyboard toward an equilibrium positiondisposed between the alternate positions; said rotary support meanshaving an axis of rotation, said rotary support means being mounted forselective adjustment of its axis of rotation along a path disposed toadjust the equilibrium position upon adjustment of said rotary supportmeans.
 2. In a light exposure system a copyboard mechanism having meansfor constraining a piece of copy; support means mounting said copyboardfor tiltable movement about a pivot axis selectively between twoalternate positions including a first position for loading and unloadingand a second working position angularly related to said first position;means for releasably constraining said copyboard in a selected one ofthe alternate positions; means for assisting movement of said copyboardbetween the alternate positions through application of an elastic forceto said copyboard at a location radially offset from the copyboard pivotaxis; said means for assisting movement of said copyboard between thealternate positions including an inextensible, flexible member having anattachment means securing one end portion of said flexible member tosaid copyboard at a location radially offset from the copyboard pivotaxis, elastic means for applying tension to said inextensible, flexiblemember and being attached to the other end portion thereof; saidcopyboard being mounted on said support means so that said copyboardpivot axis is offset from the center of gravity of said copyboard in adirection to bias said copyboarD toward one of the alternate positionsand relative to said rotary support means; means constraining saidcopyboard in a selected one of the alternate positions and beingreleasable to enable movement of said copyboard to the other one of thealternate positions; and said rotary support means being selectivelydisposed so that said copyboard arrives at the working position with asufficiently low velocity to prevent damage of the copyboard, itscomponents, and its contents.
 3. The invention according to claim 1wherein said inextensible, flexible member includes a length of rollerchain; said rotary support means including a sprocket having said chainengaged therewith.
 4. The invention according to claim 2 and furthercharacterized by detent means engageable with portions of said copyboardfor constraining the copyboard in a selected one of the two alternateextreme positions and being releasable to permit movement to thealternate one of said positions under the urging of said elastic means.